1. Field of the Invention
Embodiments disclosed herein generally relate to films having a low dielectric constant for use in the fabrication of electronic and semiconductor devices.
2. Description of the Related Art
As the semiconductor industry introduces new generations of integrated circuits (ICs) having higher performance and greater functionality, the density of the elements that form those ICs is increased, while the dimensions, size and spacing between the individual components or elements are reduced. While in the past such reductions were limited only by the ability to define the structures photolithographically, device geometries having dimensions measured in um or nm have created new limiting factors, such as the conductivity of the metallic elements or the dielectric constant of the insulating material(s) used between the elements.
In the field of advanced semiconductor fabrication, dielectrics with low K values are required for future generations of integrated circuits having design rules of less than or equal to 90 nanometers (nm) so as to reduce overall capacitance crosstalk. The term “low K dielectric” generally refers to materials having a dielectric constant that is generally less than about 3.9. More typically, for the advanced design rules, the dielectric constants of the low K dielectric materials are selected to be less than 3.0, and oftentimes less than 2.5. The dielectric films are generally deposited or formed using a spin-on process or by using a chemical vapor deposition (CVD) process.
To achieve the low K values which can be required by modern semiconductor devices, porous layers have been used to incorporate air (which has a K value of 1). Several methods have been pursued to induce porosity into low dielectric materials, such as organic, low K polymers or organic polysilica, low K polymers. One approach is to fabricate a hybrid organic-inorganic film using a mixture of silicon and organic precursors, with the film being subsequently cured using heat, electron beam (e-beam) or ultraviolet radiation (UV) to degrade the organic molecules. By degrading the organic molecules, pores are created but the mechanical strength of the layer is diminished.
Further problems arise with relation to the formation of features in the low K film. In conventional schemes, the deposited film is generally cured using either a thermal process, a UV process, an electron beam (e-beam) process or others to produce a porous film. The porous film is then undergoes etching, ashing, wet clean or other processes related to the formation of features. However, these processes can easily damage the porous low K film.
Therefore, there is a need for methods of preventing damage in ultra low K dielectric films during the fabrication of IC devices.